Romney finally finds his claws but Gingrich survives

Mitt Romney attempted to revive his flagging presidential campaign with a frontal assault on Newt Gingrich's ethics at the Republican debate in Tampa, accusing him "working as an influence peddler" and repeatedly reminding voters he was sacked as party leader in Congress for unethical behaviour.

Gingrich, who goes in to next week's Florida primary bolstered by his surprise victory in the South Carolina vote on Saturday, at times struggled to fend off Romney's barrage of accusations, which painted him as serially dishonest, untrustworthy and unfit to be president.

But Republican activists disagreed on whether the attack will do any lasting damage as polls showed that Gingrich has overturned Romney's once significant lead in the Florida race and is up to nine percentage points ahead.

After the debate, Romney's campaign also sought to put to rest days of fevered speculation about his taxes by releasing details showing that he earned $45m, mostly from investments, and paid tax at less than 15% over the past two years. His income puts him among the top 1% of earners in the US but his tax rate is considerably lower than that paid by most working Americans.